1983 JD 318 with onan - oil drain plug?

I looked in the holes through the frame on both side and no valve? I looked underneath and no drain? I took the side covers off and no drain? The oil filer is a NAPA 1348 but I did not take the engine sheild off to see if the drain was behind that. I bought the tractor in June but never asked where the oil drain is. maybe the owner before me removed a drain hose or valve?

I looked in the hole near the front wheel on both sides and there is no brass valve. This is a 1st year 318 built in 1983. Maybe the oil filter is the drain? I looked at the manual on this site and I do not have a valve like is show being opened with plyers? Boy do I feel stupid!

Former owner just called. The 1983 JD 318 is the only year the oil drain plug is underneath the tractor near the mule drive. In fact he suggested I remove the mule drive to keep it and the belt from getting oily when changing the oil. Figures I have the one year model that has the drain in a weird location!